It is proposed to further develop and test a new and easily introduced type of inracaval filtering device for the prevention of pulmonary embolism. The device will be in the form of a thin straight wire at ordinary room temperature, permitting its ready introduction into the venous circulation through a standard angiographic catheter. The catheter is prepositioned in the inferior vena cava by routine percutaneous technique and fluoroscopic control. The instant it is deposited in the inferior vena cava the device, now at body temperature, will assume a predetermined coiled-ring form previously imprinted in its thermal memory. The device will be designed to lock into position at the appropriate level, thus serving as a permanent filter in the venous blood-stream. This will interrupt future thrombo-emboli originating in the lower limbs or pelvic veins from reaching the lungs. A significant component of the effort relates to materials engineering regarding allloys which exhibit the thermal shape memory effect and which are biomedically suitable. This includes: alloy selection, alloy preparation, design of new alloy variants, characterization of alloy pprpoerties and behavior, refinement of metallurgical processing techniques, and design and implementation of device fabrication methods. It is planned that fundamental research on the physical phenomena underlying the thermal-memory effect will be undertaken in a separately funded project. While the present application is initially concerned with experimental animals, it will be extended to include human subjects at an appropriate stage. Towards the later phases of the project work will also include other potential implant applications, based on the insertion techniques developed and on a variety of special properties which can be achieved with these alloys, in addition to the shape memory effect. DTX* 1HL-20878-1*